Information on How a Hinge Joint Works

A hinge joint is a type of synovial or free moving joint. Hinge joints include the fingers, toes, elbows, knees, ankles and lower jaw. These joints may be free moving but just like hinges on a door, they only allow movement in one direction.

Significance

• The knee joint is the largest joint in the body.

  Hinge joints allow for specific movements by the body. Eating, talking, running, chewing, writing or playing a musical instrument are possible because of hinge joints. These joints have a joint capsule and strong ligaments to give strength and support.

Function

• Joints need muscle and vice versa for work to be done.

  Hinge joints work because of opposing muscle groups. The joint may be free moving but it needs the associated muscles to cause this movement. A hinge joint is either flexed or extended. There may be minor rotation of these joints but to do work, they must be extended or flexed.

Cause and Effect

• Several different hinge joints make it possible to use a phone.

  Someone reaching for a telephone is extension. He draws the phone to his face, flexion. The normal resting state of the elbow is extension. This is because of the tricep muscle in the back of the arm. To bring the phone to the face requires the tricep to relax and the bicep, in front, to shorten and cause the forearm to be drawn up, flexion.